1. Field of the Invention
The present invention relates to a speaker system, and a mobile terminal device and an electronic device including the speaker system.
2. Description of the Related Art
With reference to FIG. 27, a conventional cellular telephone 15 will be described. Japanese Laid-Open Publication No. 8-275293 discloses a speaker system for vibrating a housing of a cellular phone by a driver directly attached to the housing so as to output a vibration or sound.
The cellular phone 15 includes a housing 10, an antenna 11, a sound board 12 which is thinner in a rear peripheral portion than the rest thereof, a driver 13 provided on a rear surface of the sound board 12, and a character display panel 14 provided on a front surface of the housing 10 adjacent to the sound board 12.
An operation of the cellular phone 15 will be described. When an electric signal is applied to the driver 13, the vibration of the driver 13 is directly transferred to the sound board 12 provided in the housing 10. Then, the sound board 12 is vibrated so as to generate a sound. The sound board 12 is thinner in the rear peripheral portion than the rest thereof, so as to be easily vibrated.
The cellular phone 15 having such a structure has the following problem. Due to the sound board 12, the planar size of the character display panel 14 for displaying a phone number or the like is inevitably provided in a small, limited space below the sound board 12. Accordingly, it is conventionally difficult to enlarge the display panel 14 for more conveniently displaying, for example, characters of e-mails or images received through the Internet.
A conventional electronic device or a mobile terminal device including the above-described speaker system has the following problem. In these devices, a display panel and a speaker are located separately. Therefore, the position where the image is displayed is different from the position from which the sound is output. This gives the user a sense of unnaturalness. For example, when the electronic device or the mobile terminal device is used as a video telephone, the user has a sense of unnaturalness since the position of the image representing the person on the other end is different from the position from which his/her voice is output. It is more natural and desirable that the position where the image is displayed to the user is the same as the position from which the sound is output to the user.